Is it a good idea to send them a file to edit and an installer on the forums to recruit play testers?
Maybe I misunderstand your question, but both of those sound like bad ideas.
"file to edit" - Unless you plan to release the game as open-source, you should never send the editable file to anyone who isn't on your team or whom you don't know personally. Because if the game's any good, and you give away the project folder, somebody is probably going to steal it and perhaps release it before you even have the chance to do so yourself.
"installer" - If your game is still in development, an installer seems unnecessary. And even if your game is ready for release, an installer might not always be a good idea. Some people download the game and then see that it's an installer and then think, "Too much trouble" and delete it right off the bat. Or other people might only have access to shared computers, and they might download it but not be able to install it due to the administrator's permission settings.